private void btnXoa_Click(object sender, EventArgs e)
 {
     using (QLBanXeEntities1 quanli = new QLBanXeEntities1())
     {
         CTPHIEUNHAP hd = quanli.CTPHIEUNHAPs.Where(p => p.MaPN == cbmaPN.Text).Where(p => p.MaSP == cbmasp.Text).FirstOrDefault();
         if (hd != null)
         {
             quanli.CTPHIEUNHAPs.Remove(hd);
             quanli.SaveChanges();
             MessageBox.Show("Đã xóa!");
             frmCTPhieuNhap_Load(sender, e);
         }
     }
 }
        private void btnSua_Click(object sender, EventArgs e)
        {
            using (QLBanXeEntities1 quanli = new QLBanXeEntities1())
            {
                CTPHIEUNHAP kh = quanli.CTPHIEUNHAPs.Where(p => p.MaPN == cbmaPN.Text).Where(p => p.MaSP == cbmasp.Text).FirstOrDefault();
                //kh.MaPN = txtmaphieunhap.Text;

                kh.GiaNhap   = Convert.ToInt32(txtgianhap.Text);
                kh.SoLuong   = Convert.ToInt32(txtsoluong.Text);
                kh.ThanhTien = Convert.ToInt32(txtthanhtien.Text);

                quanli.SaveChanges();
                MessageBox.Show("Sửa thành công", "Thông báo", MessageBoxButtons.YesNo, MessageBoxIcon.Information);
                frmCTPhieuNhap_Load(sender, e);
            }
        }